1. Field of the Invention
The present invention relates to an ink cartridge detachably attached to a printing apparatus and supplying ink to a printhead of the printing apparatus which ejects ink droplets in accordance with a printing signal.
2. Related Art
Typically, a printhead of an ink-jet printing apparatus connects with an ink cartridge via an ink supply channel. The printhead is designed to receive ink from the ink cartridge. The printing apparatus is provided with a hollow ink supply needle in the ink supply channel to supply ink to the printhead. The ink cartridge is formed with an ink supply port for supplying ink to the printhead. When the ink cartridge is mounted on the printing apparatus, the hollow ink supply needle is inserted into the ink supply port of the ink cartridge and ink is supplied to the printhead via the hollow ink supply needle.
Unexamined Japanese patent applications (OPI) Nos. Hei. 5-229137 and Hei. 9-174879 disclose an ink cartridge of this structure including a valve member at an upper part of the ink supply port, i.e., inside of the ink cartridge. The ink supply port of the ink cartridge of this type opens when the ink supply needle is inserted, and closes when the ink supply needle is removed. Thus, the ink cartridge is capable of preventing leakage of ink or is capable of being repeatedly attached to the printing apparatus. On the other hand, Unexamined Japanese patent application (OPI) No. Hei. 7-232438 discloses an ink cartridge having a semiconductor memory device that stores data relating to the ink cartridge.
The conventional valve member as mentioned above, however, has a drawback as the connection between the semiconductor memory device of the ink cartridge and a control unit of the printing apparatus is inadequate. More specifically, as the valve member is always urged by a spring in an insertion direction of the ink supply needle in order to seal the ink supply port, the ink cartridge does not completely fit to a carriage of the printing apparatus because the resilient force of the spring pushes the cartridge up to some extent with respect to the carriage after the ink cartridge is mounted on the carriage. Such results in that the accurate positioning of the ink cartridge with respect to the carriage is hardly accomplished, and if a memory device is mounted on the ink cartridge, the connection of terminals of the memory device to the contact member of a circuit unit of the printing apparatus may be failed due to the deviation caused by the resilient force of the spring urging the valve member.
Further, if the conventional ink cartridge is detached from the carriage of the printing apparatus to exchange to a cartridge of different kind or type while the original ink cartridge is not depleted, the ink may leak out of the ink cartridge through the ink supply port. Such a problem would be more emphasized when the ink cartridge is recycled and the valve or packing becomes worn out and, accordingly, the sealability of the valve mechanism is deteriorated.
In addition, if the memory device comes into contact the terminal of the printing apparatus whereas the ink supply needle does not correctly enter the ink supply port and thus still not ready for supplying ink, the printing operation may start and air would be conveyed to the nozzles of the printhead. Such could result in a serious problem in giving damage to the printhead, and no recovery can be expected without exchanging the printhead. Therefore, it has been required an appropriate interrelationship of the contact electrode of the memory device with the engagement between the ink supply port and the ink supply needle.